Add a libbpf dumper function that supports dumping a representation
of data passed in using the BTF id associated with the data in a
manner similar to the bpf_snprintf_btf helper.
Default output format is identical to that dumped by bpf_snprintf_btf(),
for example a "struct sk_buff" representation would look like this:
struct sk_buff){
(union){
(struct){
.next = (struct sk_buff *)0xffffffffffffffff,
.prev = (struct sk_buff *)0xffffffffffffffff,
(union){
.dev = (struct net_device *)0xffffffffffffffff,
.dev_scratch = (long unsigned int)18446744073709551615,
},
},
...
Patches 1 and 2 make functions available that are needed during
dump operations.
Patch 3 implements the dump functionality in a manner similar
to that in kernel/bpf/btf.c, but with a view to fitting into
libbpf more naturally. For example, rather than using flags,
boolean dump options are used to control output.
Patch 4 is a selftest that utilizes a dump printf function
to snprintf the dump output to a string for comparison with
expected output. Tests deliberately mirror those in
snprintf_btf helper test to keep output consistent.
Changes since RFC [1]
- The initial approach explored was to share the kernel code
with libbpf using #defines to paper over the different needs;
however it makes more sense to try and fit in with libbpf
code style for maintenance. A comment in the code points at
the implementation in kernel/bpf/btf.c and notes that any
issues found in it should be fixed there or vice versa;
mirroring the tests should help with this also
(Andrii)
[1]
https://lore.kernel.org/bpf/1610386373-24162-1-git-send-email-alan.magu...@oracle.com/T/#t
Alan Maguire (4):
libbpf: add btf_has_size() and btf_int() inlines
libbpf: make skip_mods_and_typedefs available internally in libbpf
libbpf: BTF dumper support for typed data
selftests/bpf: add dump type data tests to btf dump tests
tools/lib/bpf/btf.h | 36 +
tools/lib/bpf/btf_dump.c | 974 ++++++++++++++++++++++
tools/lib/bpf/libbpf.c | 4 +-
tools/lib/bpf/libbpf.map | 5 +
tools/lib/bpf/libbpf_internal.h | 2 +
tools/testing/selftests/bpf/prog_tests/btf_dump.c | 233 ++++++
6 files changed, 1251 insertions(+), 3 deletions(-)
--
1.8.3.1
